1. Technical Field
The present invention relates to a shift operating device of a traveling vehicle.
2. Background Art
Conventionally, with regard to a traveling vehicle having a hydro static transmission (hereinafter, referred to as “HST”), there is a well known construction that a shift operating device, in which a forward traveling pedal and a rearward traveling pedal are separately disposed, is provided (for example, see the Patent Literature 1).
With regard to such a shift operating device, a rotary support shaft of the forward traveling pedal and a rotary support shaft of the rearward traveling pedal are provided while being shifted between their positions, and each of the rotary support shafts is connected to a control arm through a linkage mechanism. In the case that the forward traveling pedal is operated, the linkage mechanism rotates the control arm along the direction opposite to the case that the rearward traveling pedal is operated. By the rotation of the control arm, a control rod of the HST is operated so as to change the speed and reverse the traveling direction of the vehicle.
There is a well known construction that a neutral position of the forward traveling pedal and the rearward traveling pedal is set by a mechanism constructed by combining a neutral return spring, a cam follower and a cam (for example, see the Patent Literature 2).
Patent Literature 1: the U.S. Pat. No. 5,842,378
Patent Literature 2: the U.S. Pat. No. 4,759,417
However, with regard to the above-mentioned construction, the rotary support shafts of the forward traveling pedal and the rearward traveling pedal are provided while being shifted between their positions, whereby the linkage mechanism is complicated. By adjusting the angles of the pedals of the complicated linkage mechanism, many adjustment processes are required. The number of parts is many and influences manufacturing cost and the number of assembly processes.
The rotary support shafts of the forward traveling pedal and the rearward traveling pedal are provided while being shifted between their positions, it is difficult to secure arrangement space of the shafts in relation to the other devices.
With regard to the conventional mechanism setting the neutral position of the pedals, the structure is complicated. The power transmitted to the cam is dispersed at the contact point of the cam and the cam follower, whereby the transmission efficiency of the biasing force of the neutral return spring is not good. Accordingly, the setting of the neutral position is inaccurate.